Self-locking electrical connector



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l 4. l/f s R m .l M .0. Nw mm z www z m @fn m. m t. z E vqg4 w v5 EWS 1245 April Z1, 1953 Patented Apr. 21, 1953 SELF-LOCKING ELECTRICAL vCONNECTOR Carl H. J udisch, Hamden, Conn., assignor to The Whitney BlakeCompany, Hamden, Conn., a corporation of Connecticut ApplicationSeptember 27, 1949, Serial No. 118,025

6 Claims. Y (Cl. 173-361) The present invention relates to improvementsi in electrical connectors and relates more particularly to improvementsin self-locking electrical connectors which are designed and adapted tolock themselves in connected relationship with respect to a receptacleor other electrical fitting` so as to avoid accidental disconnection inthe event that lengthwise strain is placed upon the wires or cable towhich the electrical connector is attached:

As will be apparent from the following, considered in conjunction withthe accompanying drawings, the present invention contemplates a uniqueand highly effective self-locking electrical connector having a bodyformed of rubber or other suitable resilient material and havingprojecting from the said body a pair of contactprongs and a pair ofcomplemental locking arms movable toward the respective contact prongsinto unlocking position by laterally compressing the said resilientbody.

It is not alleged that the present invention is the rst wherein it isproposed to provide a selflocking `electrical connector having aresilient body which is laterally yieldable. However, as far as I amaware, all prior self-locking electrical connectors havingtransversely-yielding resilient bodies have endeavored to devolve thelocking function upon the Contact prongs themselves, in whichconstruction the lateral spacing of the contact blade has necessarily tobe'altered in order to effect the locking and unlocking. Such priorconstruction and arrangement of parts has been open to the very seriousobjections that not only is it unreliable but exceedingly awkward inuse, in view of the fact that the apertures in a companion receptacleare at fixed spacings and the shifting of the contact prongs of theself-locking connector has made it dimcult to interiit the latter with aplug-receptacle or the like.

As will also be apparent from the following, the self-locking electricalconnectors of the present invention do not require the alteration of thelateral spacing between the contact prongs, and while this latterfeature in itself is not original with the present invention, thecombination ofsuch feature with the other features herein set forth, hasresulted in a unique structure possessing' marked advantages over theprior art.

` One of the main lobjects of the present invention` is to provide asuperior self-locking electrical connector characterized by ease andfacility of use, together with reliability of operation.

"QAnother object of the present invention `is to provide an electricalconnector of the `character referred to which does not require thelateral movement of the contact prongs or members in order to eifect thelocking and unlocking actions.l

A further object of the present invention is to.A

provide a superior self-locking electrical connector which may have itsmetallic parts together with wires or cables leading therefrom, encasedin a resilient body by a simple molding operation to thus lower cost ofmanufacture and provide a connector which will not readily come apart.

Other objects and advantages will appear to those skilled in the artfrom the following, considered in conjunction with the accompanyingdrawings.

In the accompanying drawings, in which certain modes of carrying out thepresent invention are shown for illustrative purposes:

Fig. 1 is a longitudinal `sectional view taken on the line l-l of Fig. 2and showing the parts in the positions which they assume when thelocking arms are in position to interlock the electrical connector witha plug receptacle or the like;

Fig. 2 is a transverse sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a longitudinal sectional view taken onV the line 3--3 of Fig.1;

Fig. 4 is a longitudinal sectional view similar to Fig. 1 but showingthe locking arms retracted Fig. 5 is a transverse sectional view similarto Fig. 1 but taken on the line 5--5 of Fig. 4; and

Fig. 6 is a sectionalperspective View of the body taken on the centralflatwise plane thereof.

The particular self-locking electrical connector herein chosen forpurposes of illustrating a preferred embodiment of the presentinvention, is in the form of a double-pronged plug unit of the typeadapted to be thrust into and pulled out of connection with yanelectrical supply receptacle or outlet, which plug unit comprises a,resilient body generally designated by the reference character l 0, twocorresponding or like contact prongs or members, each generallydesignated by the reference character Il, and two corresponding flexiblelocking arms or members, each generallyv designated by the referencecharacter I2. As shown, the plug body is generally oblong incrosssection, with a pair of opposed relatively broad lateral faces Illaand a pair of opposed narrower lateral faces thereto.

I 0b substantially perpendicular The body I0 may be formed of anysuitable natural rubber or synthetic resins. Some of the resilientinsulating materials suitable for the present purposes are:

(1) vulcanized copolymers of styrene and butadiene,

(2) vulcanized copolymers of polyisobutylene and isoprene or butadiene,

(3) vulcanized polychloroprene,

(4) vulcanized copolymers of butadiene and acrylonitrile,

(5) vulcanized organic polysulde,

(6) Plasticized vinyl chloride polymers, and Y (7) Plasticized vinylchloride-vinyl acetate Y copolymers.

Extending axially in the inner or cord end of the body II! is a passageI3 into which is fitted the end portion of a multiple-conductor cable orcord I4 having, in the present instance, two sets of individuallyinsulated conductors I5-I5 each preferably formed of a group of nestrands of copper or the like.

Formed in the resilient body I0 and opening through its outer or prongend I6, is a pair of like prong-anchoring recesses or cavities II-I'Iwhich extend longitudinally in the said body in substantial parallelismwith each other and in spaced-apart relation on opposite sides of theplug axis. Each of the said recesses is of slotlike form incross'section with its major crosssectional transverse dimensionextending in a direction substantially perpendicular with respect to aline drawn between the tvvol recesses. The two said laterally spacedapart recesses I'I-I'I serve, in effect, to divide the one-pieceresilient body Il) into three longitudinally extending sections or armswhich are aligned, in normally spaced-apart relation, in the directionof the major cross-sectional dimension of the plug body, namelypacentral spacing-arm or section I8 extending substantially in an -axialdirec-tion away from the cable I4, parallel to and situated betweenthose portions of the contact prongs or blades which are within the plugbody IIJ; together with two outer flexible releasing arms or endsections ISI-I9 which are movable toward and away from each other andtoward and away from the spacing arm I8 in a. manner that willhereinafter appear. As compared to the flexible outer lock-controllingor releasing arms I9, the central prong-spacing arm is seen from thedrawings to be relatively massive and unyielding.

Respectively located in the recesses I'I-I'I in the body I9 are theinner portions of the conf tact prongs II-II before referred to andwhich contact prongs project at their outer ends fromV and beyond theouter end I 6 of the said body I0. Each of the said contact prongs maybe conveniently formed up of spring brass or other suitable resilientmetal, and in the instance shown is channel-like in cross-section, beingformed with parallel side flanges 20-20 which are spaced from each othera distance sufficient to freely accommodate between them the companion(J1-'associated locking-arm I2. The said flexible locking a-rm ispreferably pretensioned or biased so as to normally tend to stand inspaced relationship outwardly from its companion contact blade II as isespecially well shown in Figs. 1 and 2.

Preferably and as shown, each contact prong I I and its comp-anionlocking arm I2 are integrally united with each other at theirYrespective inner or upper ends.A Adjacent its junction with thecompanionrcontact prong II, each locking arm I2 is preferablyiiattenedtightly against the adjacent face of the said contact prong as shown,and in `this area of contact, both the contact' prong II and itscompanion locking arm I2 are jointly pierced transversely to provide anaperture through which the bared end of the adjacent one of theconductors I5 may be passed and soldered or otherwise rigidly connectedto the unit comprising the two members I I and I2.

As thus constructed and arranged, each contact prong I I is mountedagainst the inner wall of the particular recess I'I in which it islocated and is preferably firmly coupled to the said wall in anysuitablemanner such, for instance, as by being provided with anoffsetting coupling finger 2| embedded in the resilient material fromwhich the body I0 is for-med. Each locking arm I2 is located against theouter wall of the particular recess I l in which it is mounted and ispreferably firmly coupled tosuch wall in any suitable manner such, forinstance, as by striking therefrom a coupling nger 22 which is embeddedin theresilient material from which the body IB is made. At its lowerend, each resilient locking arm I2 has -1 detent or latching provision,said end being in this instance bent outwardly away from the com-V #j ofthe present invention is the secure attach-l ment of a given contactprong II to the Vinner wall of the particular recess I1 in which it ismounted and the attachment of the companion.

locking arm I2 to the outer wall of the said recess, whereby the tensionof the resilient body Iii will serve to yieldingly hold agiven lockingarm I 2 away from its companioncontact prong II, as is shown in Figs. 1and 2. In addition to or inV lieu of the attachment provided by thecoupling fingers 2l and 22, the contact prongs' II and the locking armsI2 may be secured to the respective walls of a given recess II by beingsuitably adhered to the material from which the body I isV formed, in amanner well known in the art.

Suitable cements foreffecting the adhering just above referred to arenumerous, but the fol' lowing may be mentioned by wayV of example:

(1) Cements made from solutions or dispersions of rubber conversionproducts such as are produced by the action of sulfuric acid orbenzene-sulfonie acid on natural crude rubber.

(2) Alkyd resin cements,

(3)V Polychloroprene cements, and

(4) Cements made of natural or synthetic rubber compositions containingvulcanizing agents.

It will be noted by reference to Figs. 2 and 3, in parti-cular, thateach longitudinal recess I'I has its major transverse dimension in adirection substantially perpendicular to a line vdrawn between the twosaid recesses, and this major transverse dimension is greater than thesimilar transverse dimension of both the contact prong II and companionlocking arms I I 2 mounted therein. This relationship, in effect, causesthe respective opposite edges of each of the said recesses to constitutelongitudinal clearance channels 2li-2li. As thus proportioned, eachreleasing arm I9 is integrally connected to the central spacing arm ofthe body I by means of relatively thin iiexible and compressibleconnecting webs 25-25. Y

Preferably, the body I6 is injection-molded in one piece around theelements II, I2, I4 and I5, during which molding operation suitableremovablellers .(i. e. core material) lmay be placed acaaovo 5. betweena given contact prong `Il and its "complemental locking armIZ to excludethe resilient material from therebetween, whereby to maintain themnormally spaced apart to the extent indicated in Figs. l and 2, and tolaterally extend the cross-sectional dimensions of the recesses Il `toform the clearance channels 24 and the flexible connecting webs 25.

The self-locking electrical connector above described is adapted to haveits contact prongs II-Il inserted together with the companion lockingarms i2-l2) through the usual slots or apertures in another electricalconnector of any suitable character and commonlyknownasaplug receptacle.Such plug receptacles are frequently formed interiorly with abutmentswith which the respective locking iingers 23-23 may engage to releasablycouple or interlock the connector of the present invention with suchplug receptacle, al1 in a manner well understood in the art.

To effect the insertion of the contact prong H-ll and the companionlocking arms I2-I2 into the usual slots or apertures in a plugreceptacle or the like, the body I may be squeezed by finger pressureapplied simultaneously to the respective outer faces of the flexiblereleasing arms IQ-IS of the said body. The described squeezing willcause the said releasing arms |9-I 9 to ex inwardly toward each other,thereby, in turn, inwardly flexing the locking arms lZ-lZ toward theirrespective contact prongs Il-Ii into substantially the positions inwhich the parts are shown in Figs. 4 and 5. It will be noted that whenthe body I is squeezed as just described, the locking lingers 23-23 ofthe respective locking arms I2-I 2 will be retired close to theirrespective contact prongs II-ll, as is especially well indicated in Fig.4, without materially altering the predetermined spacing between thesaid contact prongs iI-I l.

Upon the squeezing pressure above referred to being released, thelocking arms |2-I2 will be restored to substantially the positions inwhich they are shown in Figs. 1 and 2, under the combined urge of thelocking arms themselves and of the resilient material of the body I0, sothat the locking fingers 23-23 will be in position to engage with anysuitable abutments within a plug receptacle to interlock the device ofthe present invention with the said plug receptacle.

Where, as is often the case, the plug receptacle is provided withsuitably formed guide surfaces sloped to the prong receiving apertures,entry of the prong-and-locking-arm units of the present novel plugconnector construction into said apertures may obviously be effected bya simple thrusting movement, without applying the described squeezingpressure to the end sections I9 of the plug connector.

To effect the disconnection of the electrical connector of the presentinvention from a plug receptacle or the like, the squeezing action abovereferred to may be repeated and the entire connector withdrawn from theplug receptacle before the squeezing pressure referred to is relaxed.

During the squeezing of the body I0, as above described, the lockingarms IZ-l 2 move inwardly as described, without causing the materialdisplacement of the contact prongs II--II toward each other, which thusremain substantially in their predetermined spaced-apart relationships,whereby they may be readily entered into and removed from a plugreceptacle or the like.

During the described squeezing of the body l0 to effect the retirementof the locking arms 421-123 the connecting websf 25 of the "body 40s.provide, in conjunction with the clearancev chan-.a

disturbing the g spacings of the contactprongsj The invention may becarried out in other epee cific Ways than those herein set forthwithouty departing` from the spirit andessential characteristics of theinvention, andthe present em-V bodiments are, therefore, to beconsidered in `all=` respects as illustrative and not restrictive, andall changes coming within the meaning and equivalency range of theappended claims are intended to be embraced therein.

I claim:

1. A self-locking electrical connector plug comprising a plug body ofresilient insulating material having a cord end and a prong end and apair of opposed relatively broad lateral faces, a pair of contact prongsanchored Within said body and projecting from said prong end insubstantially fixed parallel relation to each other, the inner portionsof the prongs being disposed in spaced parallel slots formed within saidbody and dividing it longitudinally at this locality into a centralprong supporting and spacing section and two end sections, each of saidslots being substantially wider than the thickness of the prong disposedtherein and extending beyond both edges of said prong transversely ofsaid body toward the broad lateral faces thereof, whereby to give saidbody maximum flexibility along the slot ends, said contact prongs beingfirmly secured within their respective slots to said central supportingand spacing section; a pair of locking arms each firmly secured withinone of said slots to the adjacent end body section in spaced relation tothe contact prong secured to said section, each said arm projectingoutwardly from the open end of the slot and having detent provision forlocking engagement with cooperating detent provision in a plugreceptacle into which the plug is adapted to be thrust, said lockingarms being movable inwardly to clear the receptacle detent provision bycompressing said end sections toward said central section against theresiliency of said body material; and means connecting lead wires to theinner ends of the prongs.

2. A self-locking electrical connector as defined in claim 1, whereineach of said contact prongs is provided with side flanges adapted andarranged to permit entry between them of the respective locking armassociated with such prong.

3. A self-locking electrical connector as dened in claim 2, wherein saidcontact prongs and locking arms are formed of suitable resilient metal,and the locking arms are so biased that each normally tends to maintainthe spaced relationship between it and the contact prong with which itis associated.

4. A self-locking electrical connector as dened in claim 3, wherein eachsaid contact prong and its associated locking arm are united with eachother at their ends located within the plug body, and to those junctionsare secured the conductor terminals of a multiple conductor cord ofwhich the end portion enters said plug body.

5. A self-locking electrical connector as deiined in claim 4, whereinsaid plug body is composed of resilient insulating material molded in 7Aone piece about the'other elements specied in said claim.

6. A self-locking electrical conductor as defined in `claim 5, whereinsaid cavities, in Which are located the units each comprising acontactprong lamd an associated locking arm, extend laterally beyond both edgesof both said units to such 'a distanceas to provide that the resilientconnection of each lock-controlling section of the plug body isconstituted by relatively thin, exible and compressible webs of saidinsulating material.

CARL H. JUDISCH.

"References Cited in the. le o1' this patent UNITED STATES PA'IENTSNumber

